Add MODULE.bazel to Starlark language

[jsharpe]

Description

Adds filenames that are used by the new bzlmod format introduced in bazel 5.0.0 as an experimental feature and released in bazel 6.0.0.
Also added copy.bara.sky which is the main configuration file for Google's copybara tool.

Checklist:

• I am associating a language with a new file extension.
  • The new extension is used in hundreds of repositories on github.com
    • Search results for each extension:
      • https://github.com/search?q=path%3A**%2FMODULE.bazel&type=code
  • I have included a real-world usage sample for all extensions added in this PR:
    • Sample source(s):
      • https://github.com/bazelbuild/bazel/blob/c1168e13965ccd61ae9d948cf1e30bcdf459ae6a/MODULE.bazel
    • Sample license(s): APL 2.0
  • I have included a change to the heuristics to distinguish my language from others using the same extension.

[lildude]

Of these, only MODULE.bazel has sufficient popularity on GitHub for inclusion right now. The others are a long way off our usage requirements.

[jsharpe]

Of these, only MODULE.bazel has sufficient popularity on GitHub for inclusion right now. The others are a long way off our usage requirements.

Have update the PR to remove the ones that don't meet usage requirements. WORKSPACE.bzlmod is just a file that is used during transition to bzlmod so its usage will be expected to be low as bzlmod is adopted.

[jsharpe]

Do you need me to add a sample MODULE.bazel file?

[lildude]

Do you need me to add a sample MODULE.bazel file?

Yes please.

[lildude]

Yes please.

NM. I've added one directly to your branch.

[jsharpe]

Yes please.

NM. I've added one directly to your branch.

Thanks! Apologies for the lack of response sooner.